China Criticizes US Over Starlink 'Close Encounters'
The Chinese government has criticized the United States following two close encounters between its Tiangong space station and SpaceX's Starlink satellites. The incidents underscore the growing risks of orbital congestion and the need for advanced, autonomous space traffic management systems. The events highlight the increasing importance of collision-avoidance software and sensor fusion for assets operating in low Earth orbit.
- The two incidents occurred on July 1 and October 21, 2021, involving Starlink satellites 1095 and 2305, respectively. In both cases, the Tiangong space station, which orbits at an altitude between 340 and 450 km, had to perform "preventive collision avoidance control" to mitigate the risk. - According to a note China filed with the United Nations Office for Outer Space Affairs, the Starlink-1095 satellite maneuvered from its stable 555 km orbit to around 382 km between May and June 2021, leading to the July encounter. For the October incident, China stated the Starlink-2305 satellite was "continuously maneuvering" with an unknown strategy, making orbital errors difficult to assess. - Starlink satellites are equipped with an autonomous, on-board collision avoidance system that uses data from the U.S. Department of Defense's debris tracking system to automatically maneuver and avoid objects. SpaceX programs its satellites to initiate an avoidance maneuver when the probability of collision exceeds 1 in 1,000,000, a threshold it states is 100 times more conservative than the industry standard of 1 in 10,000. - The Starlink megaconstellation is the largest source of collision hazards in Earth's orbit; by one 2021 estimate, its satellites were involved in 1,600 weekly encounters where two spacecraft passed within 0.6 miles (1 kilometer) of each other. From December 2022 to May 2023, Starlink satellites performed over 25,000 collision avoidance maneuvers, a number which doubled to nearly 50,000 in the following six-month period. - In its complaint to the UN, China argued that under the Outer Space Treaty, states are responsible for the actions of their non-governmental entities, thereby holding the United States accountable for SpaceX's actions. - The Tiangong space station is a modular station with a total mass of about 66 tonnes, significantly smaller than the International Space Station's 450 metric tons. The core module, "Tianhe," was launched in April 2021, and the station became fully operational in 2022. - As of early 2026, SpaceX operates more than 9,400 satellites in low Earth orbit. The company has plans to expand this to a "megaconstellation" of up to 42,000 satellites to provide global internet coverage.
